Rework architecture

DiscordChatExporter.Domain/Utilities/AsyncExtensions.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace DiscordChatExporter.Domain.Utilities
+{
+    public static class AsyncExtensions
+    {
+        public static async Task ParallelForEachAsync<T>(this IEnumerable<T> source, Func<T, Task> handleAsync, int degreeOfParallelism)
+        {
+            using var semaphore = new SemaphoreSlim(degreeOfParallelism);
+
+            await Task.WhenAll(source.Select(async item =>
+            {
+                // ReSharper disable once AccessToDisposedClosure
+                await semaphore.WaitAsync();
+
+                try
+                {
+                    await handleAsync(item);
+                }
+                finally
+                {
+                    // ReSharper disable once AccessToDisposedClosure
+                    semaphore.Release();
+                }
+            }));
+        }
+    }
+}